1. Field of the Invention
This invention relates to a process for the conversion of a gaseous paraffinic feed containing ethane to liquid aromatics in the presence of a crystalline aluminosilicate zeolite-containing catalyst.
2. Description of the Prior Art
It has long been known to contact various hydrocarbon fractions and/or feeds with acidic catalysts and in particular, solid siliceous acidic catalysts--including crystalline aluminosilicate zeolites--for a wide variety of reactions including cracking, isomerization, hydrocracking, etc. Representative United States Patents disclosing such contacting with crystalline aluminosilicates are U.S. Pat. Nos. 3,140,251; 3,760,024; 3,775,501; 3,813,330; and 3,953,366.
Contacting paraffinic feedstocks with crystalline aluminosilicate zeolites is also known in the art, by far the primary reason for contacting paraffinic materials with zeolites has been for the purpose of cracking them, i.e., converting them to lower molecular weight products. Typical applications would be the use of crystalline aluminosilicate zeolites for carrying out dewaxing reactions, i.e., the cracking of paraffins to the low molecular weight materials.
The instant application is not concerned with hydrocarbon conversion in general, but rather, is concerned with the conversion of gaseous hydrocarbon feeds consisting essentially of paraffins, e.g., ethane to liquid aromatic compounds. Accordingly, the instant application in its most particular embodiment is concerned with the preparation of liquid aromatic compounds from ethane, i.e., the aromatization of ethane in commercially significant amounts. Up to now means to utilize ethane and other higher paraffins in for example associated gas or blow-by gas and other natural gases have mainly been confined to (1) separation and compression, e.g., methane is separated and the remaining paraffins including ethane are used as fuels or as liquifiable petroleum gas, (2) cracking and reforming, i.e. converting the gaseous feeds to ethylene and other related products.
The prior art contains many "disclosures" for aromatizing ethane but to applicant's knowledge there are none wherein significant or even appreciable amounts of ethane are converted to liquid aromatic compounds since ethane is relatively stable, inert and difficult to convert to aromatics. However, the instant process does convert appreciable amounts of ethane into aromatic compounds under less severe conditions than heretofore known to the art for most hydrocarbon conversion processes.
This application, as stated hereinabove is more particularly concerned with a process for producing aromatic compounds which comprises contacting, in the absence of added air or oxygen under conversion conditions, a gaseous, paraffinic feed containing a high percentage of ethane with a ZSM-5 type crystalline aluminosilicate zeolite catalyst having incorporated therein a minor amount of a metal or metal oxide wherein said metal is selected from the group consisting of a Group VIII, IIB or IB metal and mixtures thereof whereby ethane present in said gaseous feed is converted to aromatic compounds and recovering said aromatic compounds as liquids.